U.S. patent number 9,713,139 [Application Number 15/256,206] was granted by the patent office on 2017-07-18 for method for transmitting and receiving signals using multi-band radio frequencies.
This patent grant is currently assigned to LG Electronics Inc.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to Seung Hee Han, Dong Cheol Kim, Jin Sam Kwak, Yeong Hyeon Kwon, Hyun Woo Lee, Sung Ho Moon, Min Seok Noh.
United States Patent |
9,713,139 |
Han , et al. |
July 18, 2017 |
Method for transmitting and receiving signals using multi-band
radio frequencies
Abstract
A method is provided for transmitting, by a base station,
signals in a communication system. Carrier aggregation
configuration information is transmitted to a mobile station via a
primary carrier band of the mobile station. The carrier aggregation
configuration information informs the mobile station of a
subsidiary carrier band for the mobile station. Uplink control
information for the subsidiary carrier band is received from the
mobile station via the primary carrier band. The carrier
aggregation configuration information includes a physical
identification of a frequency allocation band used as the
subsidiary carrier band and a logical identification assigned to
the subsidiary carrier band for the mobile station. The physical
identification includes one of plural absolute frequency band
indexes assigned to frequency allocation bands available in the
communication system. The logical identification includes a logical
index assigned to the subsidiary carrier band identifying the
subsidiary carrier band.
Inventors: |
Han; Seung Hee (Anyang-si,
KR), Noh; Min Seok (Anyang-si, KR), Kwak;
Jin Sam (Anyang-si, KR), Kwon; Yeong Hyeon
(Anyang-si, KR), Lee; Hyun Woo (Anyang-si,
KR), Kim; Dong Cheol (Anyang-si, KR), Moon;
Sung Ho (Anyang-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
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Assignee: |
LG Electronics Inc. (Seoul,
KR)
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Family
ID: |
41322761 |
Appl.
No.: |
15/256,206 |
Filed: |
September 2, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160374064 A1 |
Dec 22, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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14962747 |
Dec 8, 2015 |
9467996 |
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14600840 |
Jan 5, 2016 |
9232519 |
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12849635 |
Feb 17, 2015 |
8958409 |
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12343295 |
Dec 25, 2012 |
8340014 |
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61016799 |
Dec 26, 2007 |
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Foreign Application Priority Data
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Mar 20, 2008 [KR] |
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10-2008-0025817 |
Aug 1, 2008 [KR] |
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10-2008-0075554 |
Aug 28, 2008 [KR] |
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10-2008-0084731 |
Sep 30, 2008 [KR] |
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10-2008-0096055 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/042 (20130101); H04W 80/02 (20130101); H04L
27/2614 (20130101); H04W 72/0413 (20130101); H04W
72/0453 (20130101); H04J 11/0069 (20130101); H04W
74/002 (20130101); H04W 88/02 (20130101); H04W
88/08 (20130101) |
Current International
Class: |
H04J
1/00 (20060101); H04W 72/04 (20090101); H04J
11/00 (20060101); H04L 27/26 (20060101); H04W
74/00 (20090101); H04W 80/02 (20090101); H04W
88/08 (20090101); H04W 88/02 (20090101) |
Field of
Search: |
;370/343,328,329,336,337,312 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1728580 |
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Feb 2006 |
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CN |
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1731771 |
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Feb 2006 |
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CN |
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1 128 573 |
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Aug 2001 |
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EP |
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1 492 275 |
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Dec 2004 |
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EP |
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1605726 |
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Jun 2005 |
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EP |
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1 850 547 |
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Oct 2007 |
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EP |
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1982816 |
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Oct 2008 |
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EP |
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2002-204204 |
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Jul 2002 |
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JP |
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2003-264524 |
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Sep 2003 |
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JP |
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2 149 518 |
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May 2000 |
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RU |
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WO 2006/104344 |
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Oct 2006 |
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WO |
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WO 2006/126079 |
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Nov 2006 |
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WO |
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WO 2007/052917 |
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May 2007 |
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WO |
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WO 2007/129540 |
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Nov 2007 |
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WO |
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Other References
Extended European Search Report for European Application No.
09830462.9 dated Mar. 26, 2013. cited by applicant.
|
Primary Examiner: Pham; Chi H
Assistant Examiner: Lopata; Robert
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This Application is a Continuation of co-pending U.S. patent
application Ser. No. 14/962,747 filed on Dec. 8, 2015 (now U.S.
Pat. No. 9,467,996 issued on Oct. 11, 2016), which is a
Continuation of U.S. patent application Ser. No. 14/600,840 filed
on Jan. 20, 2015 (now U.S. Pat. No. 9,232,519 issued on Jan. 5,
2016), which is a Continuation of U.S. patent application Ser. No.
12/849,635 filed on Aug. 3, 2010 (now U.S. Pat. No. 8,958,409
issued on Feb. 17, 2015), which is a Continuation of U.S. patent
application Ser. No. 12/343,295 filed on Dec. 23, 2008 (now U.S.
Pat. No. 8,340,014 issued on Dec. 25, 2012), which claims the
benefit under 35 U.S.C. .sctn.119(e) to U.S. Provisional
Application No. 61/016,799 filed on Dec. 26, 2007, and under 35
U.S.C. .sctn.119(a) to Korean Patent Application Nos.
10-2008-0096055 filed on Sep. 30, 2008, 10-2008-0084731 filed on
Aug. 28, 2008, 10-2008-0075554 filed on Aug. 1, 2008, and
10-2008-0025817 filed on Mar. 20, 2008, all of which are hereby
expressly incorporated by reference into the present application.
Claims
What is claimed is:
1. A method for transmitting, by a base station, signals in a
communication system, the method comprising: transmitting, to a
mobile station via a primary carrier band of the mobile station,
carrier aggregation configuration information informing the mobile
station of a subsidiary carrier band for the mobile station; and
receiving, from the mobile station, uplink control information for
the subsidiary carrier band via the primary carrier band, wherein
the carrier aggregation configuration information includes a
physical identification of a frequency allocation band used as the
subsidiary carrier band and a logical identification assigned to
the subsidiary carrier band for the mobile station, wherein the
physical identification includes one of plural absolute frequency
band indexes assigned to frequency allocation bands available in
the communication system, and wherein the logical identification
includes a logical index assigned to the subsidiary carrier band
identifying the subsidiary carrier band from among a plurality of
frequency allocation bands managed by a medium access control (MAC)
layer above a physical layer.
2. The method of claim 1, wherein a maximum value for the logical
index is smaller than that for the plural absolute frequency band
indexes.
3. The method of claim 1, wherein the logical index assigned to the
subsidiary carrier band is an integer value between `1` and `a
maximum number of frequency allocation bands managed by the MAC
layer-1`.
4. A method for receiving, by a mobile station, signals in a
communication system, the method comprising: receiving, by the
mobile station via a primary carrier band, carrier aggregation
configuration information informing the mobile station of a
subsidiary carrier band for the mobile station; and transmitting,
by the mobile station, uplink control information for the
subsidiary carrier band via the primary carrier band, wherein the
carrier aggregation configuration information includes a physical
identification of a frequency allocation band used as the
subsidiary carrier band and a logical identification assigned to
the subsidiary carrier band for the mobile station, wherein the
physical identification includes one of plural absolute frequency
band indexes assigned to frequency allocation bands available in
the communication system, and wherein the logical identification
includes a logical index assigned to the subsidiary carrier band
identifying the subsidiary carrier band from among a plurality of
frequency allocation bands managed by a medium access control (MAC)
layer.
5. The method of claim 4, wherein a maximum value for the logical
index is smaller than that for the plural absolute frequency band
indexes.
6. The method of claim 4, wherein the logical index assigned to the
subsidiary carrier band is an integer value between `1` and `a
maximum number of frequency allocation bands managed by the MAC
layer-1`.
7. A base station for transmitting signals in a communication
system, the base station comprising: a transmitter; a receiver; and
a processor configured to: control the transmitter to transmit, to
a mobile station via a primary carrier band of the mobile station,
carrier aggregation configuration information informing the mobile
station of a subsidiary carrier band for the mobile station; and
control the receiver to receive, from the mobile station, uplink
control information for the subsidiary carrier band via the primary
carrier band, wherein the carrier aggregation configuration
information includes a physical identification of a frequency
allocation band used as the subsidiary carrier band and a logical
identification assigned to the subsidiary carrier band for the
mobile station, wherein the physical identification includes one of
plural absolute frequency band indexes assigned to frequency
allocation bands available in the communication system, and wherein
the logical identification includes a logical index assigned to the
subsidiary carrier band identifying the subsidiary carrier band
from among a plurality of frequency allocation bands managed by a
medium access control (MAC) layer.
8. The base station of claim 7, wherein a maximum value for the
logical index is smaller than that for the plural absolute
frequency band indexes.
9. The base station of claim 7, wherein the logical index assigned
to the subsidiary carrier band is an integer value between `1` and
`a maximum number of frequency allocation bands managed by the MAC
layer-1`.
10. A mobile station for receiving signals in a communication
system, the mobile station comprising: a transmitter; a receiver;
and a processor configured to: control the receiver to receive, via
a primary carrier band, carrier aggregation configuration
information informing the mobile station of a subsidiary carrier
band for the mobile station; and control the transmitter to
transmit uplink control information for the subsidiary carrier band
via the primary carrier band, wherein the carrier aggregation
configuration information includes a physical identification of a
frequency allocation band used as the subsidiary carrier band and a
logical identification assigned to the subsidiary carrier band for
the mobile station, wherein the physical identification includes
one of plural absolute frequency band indexes assigned to frequency
allocation bands available in the communication system, wherein the
logical identification includes a logical index assigned to the
subsidiary carrier band identifying the subsidiary carrier band
from among a plurality of frequency allocation bands managed by a
medium access control (MAC) layer.
11. The mobile station of claim 10, wherein a maximum value for the
logical index is smaller than that for the plural absolute
frequency band indexes.
12. The mobile station of claim 10, wherein the logical index
assigned to the subsidiary carrier band is an integer value between
`1` and `a maximum number of frequency allocation bands managed by
the specific layer-1`.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method for transmitting and
receiving signals, wherein multi-band IDs are specified in order to
efficiently manage multi-band Radio Frequencies (RFs) in a
communication system that supports multi-band RFs and ID-related
information is signaled to transmit and receive signals.
The following description is given mainly focusing on a downlink
(DL) mode in which a base station transmits signals to one or more
terminals. However, it will be easily understood that the principle
of the present invention described below can be directly applied to
an uplink (UL) mode simply by reversing the procedure of the DL
mode.
A technology in which one entity corresponding to a specific layer
above the physical layer manages multiple carriers or frequency
allocation bands (or simply frequency allocations (FAs)) has been
suggested to efficiently use multiple bands or multiple
carriers.
FIG. 1, including view (a) and view (b), schematically illustrates
a method for transmitting and receiving signals using multi-band
RFs.
In FIGS. 1(a) and 1(b), PHY0, PHY1, PHY n-2, and PHY n-1 represent
multiple bands according to this technology and each of the bands
may have a Frequency Allocation (FA) band size allocated for a
specific service according to a predetermined frequency policy. For
example, the band PHY0 (RF carrier 0) may have a band size
allocated for a general FM radio broadcast and the band PHY1 (RF
carrier 1) may have a band size allocated for mobile phone
communication. Although each frequency band may have a different
band size depending on the characteristics of the frequency band,
it is assumed in the following description that each Frequency
Allocation band (FA) has a size of A MHz for ease of explanation.
Each FA can be represented by a carrier frequency that enables a
baseband signal to be used in each frequency band. Thus, in the
following description, each frequency allocation band will be
referred to as a "carrier frequency band" or will simply be
referred to as a "carrier" as it may represent the carrier
frequency band unless such use causes confusion. As in the recent
3GPP LTE-A, the carrier is also referred to as a "component
carrier" for discriminating it from a subcarrier used in the
multicarrier system.
From this aspect, the "multi-band" scheme can also be referred to
as a "multicarrier" scheme or "carrier aggregation" scheme.
In order to transmit signals through multiple bands, as shown in
FIG. 1(a), and to receive signals through multiple bands, as shown
in FIG. 1(b), both the transmitter and the receiver need to include
an RF module for transmitting and receiving signals through
multiple bands. In FIG. 1, the method of configuring a "MAC" is
determined by the base station, regardless of the DL or UL
mode.
Simply stated, the multi-band scheme is a technology in which a
specific layer entity (for example, one MAC entity), which will
simply be referred to as a "MAC" unless such use causes confusion,
manages and operates a plurality of RF carriers to transmit and
receive signals. RF carriers managed by one MAC do not need to be
contiguous. Accordingly, this technology has an advantage of high
flexibility in management of resources.
For example, frequencies may be used in the following manner.
FIG. 2 illustrates an example wherein frequencies are allocated in
a multi-band-based communication scheme.
In FIG. 2, bands FA0 to FA7 can be managed based on RF carriers RF0
to RF7. In the example of FIG. 2, it is assumed that the bands FA0,
FA2, FA3, FA6, and FA7 have already been allocated to specific
existing communication services. It is also assumed that RF1 (FA1),
RF4 (FA4), and RF5 (FA5) can be efficiently managed by one MAC (MAC
#5). Here, since the RF carriers managed by the MAC need not be
contiguous as described above, it is possible to more efficiently
manage frequency resources.
In the case of downlink, the concept of the multi-band-based scheme
described above can be exemplified by the following base
station/terminal scenario.
FIG. 3 illustrates an example scenario in which one base station
communicates with a plurality of terminals (UEs or MSs) in a
multi-band-based scheme.
In FIG. 3, it is assumed that terminals 0, 1, and 2 have been
multiplexed. The base station 0 transmits signals through frequency
bands managed by carriers RF0 and RF1. It is also assumed that the
terminal 0 is capable of receiving only the carrier RF0, the
terminal 1 is capable of receiving both the carriers RF0 and RF1,
and the terminal 0 is capable of receiving all the carriers RF0,
RF1, and RF2.
Here, the terminal 2 receives signals of only the carriers RF0 and
RF1 since the base station transmits only the carriers RF0 and
RF1.
However, the above multi-band-based communication scheme has only
been conceptually defined and an ID specification method, which
enables more efficient management of each frequency allocation
band, and a method for signaling ID-related information have not
been defined in detail.
SUMMARY OF THE INVENTION
An object of the present invention devised to solve the problem
lies on providing a method for transmitting and receiving signals,
wherein ID information of multiple frequency bands is specified in
a multi-band-based communication system and a method for
efficiently signaling ID-related information to achieve improved
signal transmission and reception.
Another object of the present invention devised to solve the
problem lies on providing a method for transmitting ID information
of multiple frequency bands while overcoming the Peak-to-Average
Ratio (PAPR) problem.
In accordance with an embodiment of the present invention, the
above and other objects can be achieved by providing a method for
transmitting signals, the method including transmitting an
information unit of a specific layer above a physical layer through
a plurality of frequency allocation bands managed by an entity
corresponding to the specific layer, and transmitting control
information identifying each of the plurality of frequency
allocation bands, wherein each of the plurality of frequency
allocation bands managed by the entity has a band size for
allocation for a specific service according to a predetermined
frequency policy and the control information identifying each of
the plurality of frequency allocation bands includes a second ID
into which a first ID has been converted, the first ID identifying
each of the plurality of frequency allocation bands in the physical
layer, the second ID identifying each of the plurality of frequency
allocation bands managed by the entity in the physical layer.
Here, the control information may include the first ID and the
second ID for each of the plurality of frequency allocation bands
managed by the entity and may be transmitted through at least one
of a preamble or a control signal.
When the control information is transmitted through the preamble,
the control information may be identified through a different
preamble code or a different preamble timing offset. Here, the
preamble timing offset may be applied as a timing offset of the
entirety of a frame including the preamble.
In addition, the control information of each of the plurality of
frequency allocation bands managed by the entity may be
individually specified for each of the plurality of frequency
allocation bands. Alternatively, the plurality of frequency
allocation bands managed by the entity may be divided into at least
one primary carrier frequency band and at least one subsidiary
carrier frequency band, and the at least one primary carrier
frequency band may be set to include control information of a
predetermined number of subsidiary carrier frequency bands.
Here, the at least one primary carrier frequency band may include a
plurality of primary carrier frequency bands. In this case, each of
the plurality of primary carrier frequency bands may be used to
transmit information of a predetermined number of subsidiary
carrier frequency bands.
In accordance with another embodiment of the present invention, the
above and other objects can be achieved by providing a method for
receiving signals, the method including receiving an information
unit of a specific layer above a physical layer through a plurality
of frequency allocation bands managed by an entity corresponding to
the specific layer, and receiving control information identifying
each of the plurality of frequency allocation bands, wherein each
of the plurality of frequency allocation bands managed by the
entity has a band size for allocation for a specific service
according to a predetermined frequency policy and the control
information identifying each of the plurality of frequency
allocation bands includes information of a second ID into which a
first ID has been converted, the first ID identifying each of the
plurality of frequency allocation bands in the physical layer, the
second ID identifying each of the plurality of frequency allocation
bands managed by the entity in the physical layer.
According to each of the embodiments of the present invention
described above, it is possible to more efficiently manage a
plurality of carrier frequency bands managed by one entity and the
receiving side can more easily set a procedure for receiving
signals through a plurality of carriers.
In addition, according to the embodiment wherein a timing offset is
applied to the entirety of a frame or to a preamble (synchronous
channel) transmitted in the frame, it is possible to distribute the
time of signal transmission, thereby reducing the PAPR.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention, illustrate embodiments of the
invention and together with the description serve to explain the
principle of the invention.
In the drawings:
FIG. 1, including view (a) and view (b), schematically illustrates
a method for transmitting and receiving signals using multi-band
RFs.
FIG. 2 illustrates an example wherein frequencies are allocated in
a multi-band-based communication scheme.
FIG. 3 illustrates an example scenario in which one base station
communicates with a plurality of terminals (UEs or MSs) in a
multi-band-based scheme.
FIG. 4 illustrates an example method for identifying a carrier ID
using a preamble timing offset according to this embodiment.
FIG. 5 illustrates another embodiment of the method for identifying
a carrier ID using a preamble timing offset.
FIG. 6 illustrates another embodiment of the method for identifying
a carrier ID using a preamble timing offset.
FIGS. 7 and 8 illustrate another embodiment of the method for
identifying a carrier ID using a preamble timing offset.
FIG. 9 illustrates the concept that all carrier-related control
information is transmitted using a primary carrier according to an
embodiment of the present invention.
FIG. 10 illustrates the concept that one primary carrier is
specified and the primary carrier controls remaining subsidiary
carriers.
FIG. 11 illustrates the concept that two primary carriers are
specified and each of the two primary carriers controls a
predetermined number of subsidiary carriers.
FIG. 12 illustrates a method in which a plurality of primary
carriers supports each group including a plurality of terminals
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Reference will now be made in detail to the preferred embodiments
of the present invention with reference to the accompanying
drawings. The detailed description, which will be given below with
reference to the accompanying drawings, is intended to explain
exemplary embodiments of the present invention, rather than to show
the only embodiments that can be implemented according to the
invention.
The following detailed description includes specific details in
order to provide a thorough understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without such specific details.
In some instances, known structures and devices are omitted or are
shown in block diagram form, focusing on important features of the
structures and devices, so as not to obscure the concept of the
present invention. The same reference numbers will be used
throughout this specification to refer to the same or like
parts.
The present invention suggests an ID specification method, which
allows one MAC to efficiently manage a plurality of RF carriers,
and a method for signaling ID-related information. In the following
description, the term "Media Access Control (MAC) layer" is used as
a general term describing a layer (for example, a network layer)
above the Physical (PHY) layer (Layer 1) among the 7 OSI layers,
which is not necessarily limited to the MAC layer. Although the
following description has been given with reference to an example
where multi-band RFs are contiguous, the multiple bands according
to the present invention do not necessarily include physically
contiguous RF carriers as described above with reference to FIG. 2.
In addition, although the bandwidth of each RF carrier is described
below as being equal for ease of explanation, the present invention
may also be applied to the case where the bandwidths of frequency
bands managed based on each RF carrier are different. For example,
an RF frequency band (RF0) of 5 MHz and an RF frequency band (RF1)
of 10 MHz may be managed by one MAC entity.
In addition, although RF carriers in the present invention may be
those of the same system, the RF carriers may also be those to
which different Radio Access Technologies (RATs) are applied. For
example, we can consider an example wherein the 3GPP LTE technology
is applied to RF0 and RF1, the IEEE 802.16m technology is applied
to RF2, and the GSM technology is applied to RF3.
An embodiment of the present invention suggests that the position
of each frequency band in an actual physical layer managed by one
MAC be managed by conversion into a logical index. In addition, it
is assumed that the maximum number of RF carriers managed by one
MAC in one system is limited to M.
The following is a detailed description with reference to the
example of FIG. 2 wherein the MAC #5 manages RF carriers.
In the example of FIG. 2, it is assumed that the maximum number of
RF carriers managed by one MAC is 3. It is also assumed that the 3
RF carriers are named RF1, RF4, and RF5 which are absolute
frequency band index values. In this case, the physical frequency
indices RF1, RF4, and RF5 can be managed by conversion into logical
indices 0, 1, and 2 according to this embodiment.
Accordingly, there is a need to provide a method for signaling
carrier-ID-related information to the receiving side according to
this embodiment. Signaling of the maximum number of carriers
managed by one MAC may be needed in some cases.
When the maximum number of carriers managed by one MAC is M, this
embodiment suggests two ID signaling methods: 1) a method in which
ID information is transmitted through a preamble and 2) a method in
which ID information is transmitted through a common control
signal, a broadcast channel, or the like. Possible methods for
signaling ID information using a preamble include a method in which
a different signature is included in a preamble to be transmitted
and a method in which an offset is applied to the timing of
transmission of a preamble. Applying an offset to the preamble
transmission timing may be construed as applying the offset not
only to the timing of transmission of the preamble but also to the
timing of transmission of the entirety of a frame including the
preamble.
Although it is assumed in the above example that one carrier
includes one carrier ID, it is also possible to define one logical
carrier ID into which one or more physical carrier IDs are grouped.
Here, the preamble is a signal that is transmitted through a
synchronous channel. Accordingly, the preamble will be used as a
concept identical to or including the synchronous channel.
First, reference will be made to a method for selectively signaling
information regarding the number of carriers managed by one MAC
together with each carrier ID as described above through a
preamble.
As an example of the carrier ID signaling method described above,
an embodiment of the present invention suggests a method in which a
different signature is allocated to each carrier ID. As a specific
method for providing a different signature for each carrier ID,
this embodiment suggests a method in which a different code is
allocated to each carrier ID and a method in which each carrier ID
is indicated by a preamble transmission timing offset or a frame
transmission timing offset.
Although this embodiment has been described such that one preamble
is transmitted per carrier for ease of explanation, a plurality of
preambles may also be transmitted per carrier.
It is possible to apply the same concept as described above if
synchronous channel configurations such as a P-SCH and an S-SCH
which will be used in the 3GPP LTE evolution are grouped and the
group is regarded as a preamble in this embodiment.
Reference will now be made to a method for allocating a different
code to each carrier ID as a more specific embodiment of the
present invention.
First, this embodiment suggests a method for indicating a different
carrier ID through a different code. Generally, a preamble is used
to detect a cell ID. For example, when there is a need to identify
a total of 114 cell IDs, it is required that they be identified
using at least 114 different codes and, when there is a need to
identify 4 additional carrier IDs according to this embodiment, it
is required that a total of 456 (=114*4) different codes be
allocated. Here, the term "different codes" refers to codes that
can be discriminated from each other and may be a set of codes
which are correlated with each other at a predetermined correlation
level or less, a set of circular shift sequences, a set of
sequences covered by orthogonal sequences, or the like and need not
be limited to any specific code types.
In addition, another embodiment of the present invention using the
above concept suggests that carriers representing respective
frequency allocation bands be discriminated and used according to
the usages of the carriers.
Specifically, this embodiment suggests that at least one of a
plurality of carriers be defined as a primary carrier. This primary
carrier is a carrier, for which the terminal initially attempts to
search when initial cell search or initial neighbor cell search is
performed. Generally, the primary carrier can be used to transmit a
system configuration indicating a multi-carrier configuration or a
system bandwidth, a common control signal, or broadcast
information. In this case, the terminal only needs to determine
whether the corresponding carrier is a primary carrier or a
different carrier which is referred to as a "subsidiary carrier" in
the following description.
In this case, it is preferable that two codes be additionally
allocated in order to identify the usage of each carrier. Here, it
is to be noted that the purpose of the two additionally allocated
codes is not to identify carrier IDs in the above example. In this
example, when the number of carrier IDs is 114, the total number of
needed codes is 228 (=114*2).
Reference will now be made to a method for identifying a carrier ID
using a preamble timing offset as another embodiment of the present
invention.
FIG. 4 illustrates an example method for identifying a carrier ID
using a preamble timing offset according to this embodiment.
In this example, a primary carrier and a subsidiary carrier are
discriminated (i.e., identified) using two types of preamble
signatures. More specifically, a signature 0 is used for the
primary carrier and a signature 1 is used for the subsidiary
carrier in the example of FIG. 4.
In this example, a timing offset value of one carrier unit is set
to "d" as shown in FIG. 4. The "d" value may be set to various
values as described below.
First, in an embodiment of the present invention, the "d" value can
be set to be less than a preamble transmission period or a
synchronous channel transmission period. For example, in the case
of the 3GPP LTE system, P-SCH and S-SCH signals included in a
synchronous channel are transmitted every 5 ms which is the length
of a subframe (where the P-SCH signal will hereinafter be referred
to as a "Primary Synchronization Signal (PSS)" and the S-SCH signal
will hereinafter be referred to as a "Secondary Synchronization
Signal (SSS)") and two pairs of PSSs and SSSs are transmitted in a
10 ms frame including two subframes.
Two SSSs transmitted in 10 ms have different signatures (for
example, two short swapped sequences) so that the receiving side
can determine whether a corresponding subframe in a 10 ms frame is
a subframe 0 or a subframe 1. Under this assumption, the "d" value
can be set to 5 ms.
In another embodiment of the present invention, the "d" value can
be set to be equal to or greater than the preamble transmission
period or the synchronous channel transmission period. For example,
in the case of the 3GPP LTE system, it may be difficult to derive,
from only the synchronous channel, the "d" value set to be equal to
or greater than the synchronous channel transmission period since
the same SSS is repeated every 10 ms in the 3GPP LTE system. In
this case, this embodiment suggests that the "d" value be derived
through a System Frame Number (SFN).
In the 3GPP LTE system, the SFN is transmitted through a P-BCH
included in a subframe 0 (0-4905). When it is assumed that the "d"
value has been set to 10 ms, the SFN of the carrier 0 is 10 and the
SFN of the carrier 1 is 11 and therefore it is possible to derive
the "d" value. The SFN is incremented by one every 10 ms.
A different "d" value may be set for each RF carrier. Here, the "d"
value may have a circular shift form on an OFDM symbol basis or may
be a delay value on a smaller unit basis.
When the delay value is controlled in a circular shift form, this
can be directly applied to the time domain or can be applied to the
frequency domain. A circular shift may be set to be equally applied
to every signal (for example, a Reference Signal (RS) and data)
transmitted through each carrier band or a circular shift may be
set to be applied to only the reference signal or the preamble.
That is, while transmission data is left unchanged, only the
reference signal or the preamble can be transmitted so as to have
an offset according to the "d" value. In another method, while
transmission data is left unchanged, only the SFN transmitted in
the P-BCH can be incremented. This can replace the above method in
which the preamble/synchronous channel or reference signal is
transmitted with an offset applied thereto according to the "d"
value. A method in which transmission data elements are also
transmitted with an offset applied thereto and the SFN is set to be
incremented accordingly may also be applied.
For reference, the SFN in the 3GPP LTE system consists of 12 bits.
The more significant 10 bits among 12 bits are explicitly
transmitted through a P-BCH corresponding to 40 ms and may have a
value of 0-1023 during 40 ms. The less significant 2 bits among the
12 SFN bits can be derived through blind decoding based on a unique
start position (RV) of a circular buffer.
When a timing offset is applied to a signal transmitted through
each carrier band as in the above embodiment, it is possible to
achieve an advantage of reduction in the PAPR of the transmission
signal. Here, let us assume that four carriers are transmitted
using one RF module in the 3GPP LTE system. In this case, a problem
may occur in the PAPR since four carriers are all transmitted based
on the same physical cell ID. However, it is possible to achieve an
advantage of reduction in the PAPR by setting a different
transmission timing for each carrier band as described above.
Accordingly, according to the above embodiment, the method in which
a different timing offset is applied to each carrier can also be
used to reduce the PAPR. Here, to apply a different timing offset
to each carrier, the circular shift may be applied both in the time
domain and in the frequency domain as described above.
In addition, in another embodiment of the present invention, it is
possible to set the "d" value in various manners so that the
receiving side can determine the "d" value through combination of
the preamble/synchronous channel and the SFN described above.
For example, although the "d" value is set on the basis of a P-BCH
(10 ms) to apply an offset in the above description, it is also
possible to set the "d" value on the basis of four P-BCHs (i.e., on
a 40 ms basis) to apply an offset.
The embodiment as shown in FIG. 4 has an advantage in that a
corresponding carrier ID can be efficiently detected through a
small amount of calculation. The embodiment as shown in FIG. 4 also
has an advantage in that there is no need to perform additional
control signaling for carrying the carrier ID. For example, the
terminal (Mobile Station (MS) or User Equipment (UE)) may perform
initial processes for signal processing in the following order. 1.
The terminal searches for a primary carrier through a preamble
signature "0" (i.e., carrier ID=0) and achieves time
synchronization. 2. The terminal achieves time synchronization
through a preamble of a signature "1" for a specific carrier. 3.
The terminal detects a current carrier ID using a time offset from
the primary carrier.
FIG. 5 illustrates another embodiment of the method for identifying
a carrier ID using a preamble timing offset.
In the example of FIG. 5, all carriers use the same preamble
signature (code) and the carrier ID is represented by a timing
offset. Here, it is preferable that an indicator representing the
carrier ID be transmitted at a position adjacent to the preamble of
the primary carrier in order to provide a reference for timing
offset comparison. In FIG. 5, this indicator is shown by "Primary
carrier ID indicator".
According to this embodiment, for example, the terminal may perform
initial processes for signal processing in the following order. 1.
The terminal searches for a primary carrier through a preamble
signature "0" and a primary carrier indicator (i.e., carrier ID=0)
and achieves time synchronization. 2. The terminal achieves time
synchronization through a preamble of a signature "0" for a
specific carrier. 3. The terminal detects a current carrier ID
using a time offset from the primary carrier.
The following is a description of another example of transmission
of carrier ID information for each carrier, similar to the
embodiment of FIG. 5.
FIG. 6 illustrates another embodiment of the method for identifying
a carrier ID using a preamble timing offset.
In the method of the embodiment shown in FIG. 6, a control signal
indicating the carrier ID is transmitted in each carrier. In this
case, once a carrier ID is detected, the terminal can detect all
remaining carrier IDs at the preamble detection step without
decoding corresponding control signal information.
FIGS. 7 and 8 illustrate another embodiment of the method for
identifying a carrier ID using a preamble timing offset.
Specifically, although the method of FIG. 7 is similar to that of
FIG. 6, an ID indicator for the primary carrier and an ID indicator
for the subsidiary carrier are separately transmitted in the method
of FIG. 7. Although the method of FIG. 8 is similar to that of FIG.
6, a different preamble code is used for each carrier ID and
different carrier indication information is also defined for each
carrier ID in the method of FIG. 8.
While the main feature of the above embodiments of the present
invention is that information regarding a carrier ID is transmitted
using a timing offset, carrier information may be transmitted using
various other methods. Applying an offset to the preamble
transmission timing in the embodiments described above with
reference to FIGS. 4 to 8 can be considered identical to applying a
time offset to the entirety of a frame including the corresponding
preamble to transmit information regarding the carrier ID.
An embodiment wherein carrier-related information according to the
present invention is transmitted through a common control channel
(broadcast channel) can also be provided. A carrier ID defined
according to the present invention can be transmitted through a
broadcast channel or a control signal for each carrier. For
example, in the case of the IEEE 802.16m supporting the legacy
mode, a carrier ID can be signaled using a reserved bit among 5
DLFP bits of a broadcast channel used in the conventional IEEE
802.16e and can also be signaled through a DL-MAP. Alternatively, a
new DLFP/DL-MAP format may be defined to transmit the carrier ID.
In the case of 3GPP LTE, a carrier ID can be transmitted through a
broadcast channel (BCH).
More specifically, in the case of 3GPP LTE, information indicating
whether the corresponding carrier is a primary carrier or a
subsidiary carrier can be transmitted using 1-bit signaling through
a Physical Broadcast Channel (P-BCH). That is, the primary carrier
may be signaled through a bit value "0" and the subsidiary carrier
may be signaled through a bit value "1" in the P-BCH.
Alternatively, the primary carrier may be signaled through a bit
value "1" and the subsidiary carrier may be signaled through a bit
value "0" in the P-BCH. Here, the primary carrier is a carrier that
the terminal initially attempts to access as described above.
Reference will now be made to a method for transmitting a control
signal (a carrier-related control signal such as a carrier ID)
through a primary carrier as another embodiment of the present
invention.
This embodiment suggests that all carrier IDs or control signals
managed by a MAC be transmitted using a primary carrier defined
according to an embodiment of the present invention. When all
carrier-ID-related information is transmitted using the primary
carrier, carrier indices that can be managed by one MAC, logical
indices of available frequency bands, or physical indices occupied
by the subsidiary carrier can be set to be transmitted using the
primary carrier. In the description of the present invention, the
MAC is only an example of a specific layer which is located above
the physical layer and which can manage a plurality of carriers as
described above. The "MAC" includes not only the concept defined in
IEEE but also the concept of a MAC present for each carrier band in
the 3GPP system.
The following is a description of the example illustrated in FIG.
2. Here, let us assume that the bands FA1, FA4, and FA5 are
frequency allocation bands available in the multi-carrier-based
system while the band FA1 is a primary carrier frequency band. In
this case, multi-carrier-related control information can be
transmitted through the primary carrier frequency band FA1
according to this embodiment. Since the bands FA0 to FA7 can be
used in the system in this embodiment, carrier indices 1, 4, and 5
covered by the corresponding MAC can be transmitted as a control
signal of the primary carrier. In an alternative method, when the
indices 1, 4, and 5 of the physical channels FA1, FA4, and FA5 are
converted to logical indices, it is possible to signal a logical
index 0 located at the physical channel FA1, a logical index 1
located at the physical channel FA4, and a logical index 2 located
at the physical channel FA5 in the primary carrier. It is also
possible to transmit all the control signals described above.
FIG. 9 illustrates the concept that all carrier-related control
information is transmitted using a primary carrier according to an
embodiment of the present invention.
Here, the control signals transmitted in the primary carrier
include all types of control signals described above such as a
carrier-related control signal, a general control signal, and a
carrier ID as conceptually illustrated in FIG. 9.
In the above embodiments, the preamble of each carrier in the case
where a control signal is transmitted using the primary carrier may
or may not be identical. The method in which all carrier-related
information is transmitted using the primary carrier according to
the embodiments can be used in combination with the embodiment
wherein carrier information is transmitted using the preamble.
In the above description, carriers managed by one MAC include only
one primary carrier. However, carriers managed by one MAC may
include a plurality of primary carriers and the following
description will be given focusing on the case where two or more
primary carriers are included in carriers managed by one MAC.
A method in which carrier-related information is separately defined
and transmitted using a preamble, a timing offset, or the like and
a method in which all carrier-related information is transmitted
using a primary carrier can both be applied according to the
present invention. However, the following description will be given
focusing on the case where all carrier-related information is
transmitted using a primary carrier for ease of explanation.
FIG. 10 illustrates the concept that one primary carrier is
specified and the primary carrier controls remaining subsidiary
carriers.
FIG. 11 illustrates the concept that two primary carriers are
specified and each of the two primary carriers controls a
predetermined number of subsidiary carriers.
In the method illustrated in FIG. 10, one primary carrier signals
and manages all carrier-related information of the n-1 remaining
carriers. On the other hand, in the method illustrated in FIG. 11
according to this embodiment, two primary carriers transmit
carrier-related information of two groups of subsidiary carriers,
into which all remaining subsidiary carriers are divided,
respectively.
When a plurality of primary carriers is specified according to this
embodiment as shown in FIG. 11, there is an advantage in that it is
possible to support more flexible configurations when a number of
terminals are multiplexed. For example, let us assume that one MAC
manages 6 carriers, the number of terminals belonging to the MAC is
6, and the 6 terminals are divided into two groups, each including
3 terminals. In this case, it is possible to support terminals
corresponding to each group in the following manner.
FIG. 12 illustrates a method in which a plurality of primary
carriers supports each group including a plurality of terminals
according to an embodiment of the present invention.
In this method, an RF carrier 0 and an RF carrier 3, which are
primary carriers, can manage information regarding remaining
carriers and 2 groups of terminals (MSs) into which 6 terminals are
divided can be allocated respectively to 2 carrier groups managed
by the respective primary carriers to provide services.
Although 6 terminals are divided into 2 groups to perform
communication in the example of FIG. 12, the terminals may be
divided into n groups (other than 2 groups) according to the number
of primary carriers to receive services.
The detailed description of the preferred embodiments of the
present invention has been given to enable those skilled in the art
to implement and practice the invention. Although the invention has
been described with reference to the preferred embodiments, those
skilled in the art will appreciate that various modifications and
variations can be made in the present invention without departing
from the spirit or scope of the invention described in the appended
claims. Accordingly, the invention should not be limited to the
specific embodiments described herein, but should be accorded the
broadest scope consistent with the principles and novel features
disclosed herein.
The signal transmission/reception method according to each of the
above embodiments of the present invention can be widely used for a
multi-carrier system in which one MAC entity manages a plurality of
carrier frequency bands as described above. That is, the signal
transmission/reception method according to each of the above
embodiments of the present invention can be applied to any system,
regardless of whether it is a 3GPP LTE system or an IEEE 802.16m
system, provided that the system is applied as a multi-carrier
system as described above.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
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